1. Field of the Invention
The invention concerns a rotating or swiveling device, in particular an NC circular milling attachment with a machine component on bearings on a support and able to rotate or swivel on bearings, and a clamping device for releasable fixing of the machine part in desired angled positions.
2. Discussion of Related Art
In order to carry out multi-axle machining in a single clamping cycle, multiple numerically-controlled circular milling attachments, which are able to turn and swivel, are fitted in modern machining centers and in universal milling and drilling machines. In this way it is, for example, possible to carry out in a single clamping using the controlled linear axles of the machine as well as the swiveling and rotating axle of an NC circular milling attachment, a five-axle machining cycle of workpieces of even complex shape, where time and precision losses due to repeated reclamping of workpieces are avoided. For the performance of certain machining operations, rotating and swiveling circular milling attachments must nevertheless be able to be fixed in desired rotating or angled positions. This can be carried out, for example, via the position control of the driving motors for the swiveling or turning movement of the milling attachment. In so doing it is, however, necessary for the driving motors to furnish a relatively high retention moment, so that the milling attachment is protected from distortion, notwithstanding the potentially high forces which occur, for example, in roughing-down machining. For this purpose, it is, as a rule, necessary for the driving motors to be commensurately large.
For this reason, rotating and swiveling tables have in the past been proposed, where a milling attachment able to run on bearings on a console is drawn against the console by means of a separate clamping device, to give protection against distortion. For this purpose, hydraulically adjustable tension elements were introduced which grip into a T- shaped ring groove on the underside of the table top and draw the latter with its underside against a corresponding opposite face of the console in order to ensure secure fixing which is protected from distortion. The drawback of this solution is the fact that owing to having been drawn against the console, the table top is lowered and possibly also deformed, which can lead to a loss of machining precision. Moreover, every time the table top is drawn against the console, the milling attachment bearing also comes under appreciable stress which can lead to the appearance of symptoms of premature wear.
It is a primary purpose of the present invention to create a rotating or swiveling device of the type described earlier, which makes possible the secure fixing of the rotating or swiveling machine component without a change of position.
This purpose is accomplished by the device according to the invention through the clamping device having a clamping component arranged on the support with laterally flexible clamping elements for gripping a ring groove on the rotating or swiveling machine component and a pressure component able to move against the clamping component for pressing the clamping elements against at least one side wall of the ring groove.
In the case of the rotating and swiveling device according to the present invention, the clamping of the machine component on bearings on a support so as to be able to rotate or swivel takes place solely through radial clamping forces which do not result in any drawing of the machine component to the support. In the case of a horizontal table top, it is, for example, possible to avoid, by means of radial clamping, a lowering or a deformation of the milling attachment and the resulting lack of machining precision.
Thus, a particularly advantageous embodiment of the clamping component is a clamping ring which can be fastened on the support by means of inner and outer clamping elements which are regularly distributed over its circumference and which are able to be pressed against the inner and outer side wall of the ring groove. The radial forces acting on the inner and outer side wall of the ring groove cancel out one another, so that in clamping, no lateral displacement of the rotating or swiveling machine component with respect to the support takes place.
In a further advantageous embodiment of the invention, it is also possible to achieve an even pressure over a larger area through the fact that the clamping elements are ring segments which exhibit flexibility in radial directions.
In a still further advantageous embodiment of the invention, the pressure component has the shape of a conical ring with conical pressure faces arranged between the inner and outer clamping elements. Through the wedge- and cone-shaped pressure component, it is possible to achieve an increase of the radial tension forces.
The ring groove and the associated clamping component are advantageously arranged in the area of the outer circumference of the rotating or swiveling machine component. In this way, it is possible to achieve a relatively high retention moment even by means of relatively low clamping forces.
In a readily controllable embodiment, the axial displacement of the pressure component takes place through a pressure medium actuated piston cylinder device which contains, for example, several hydraulic cylinders regularly distributed over the circumference. The pressure component can, however, also be displaced by means of other suitable actuating devices.